Hub and shaft coupling



Se t. 3, 1968 G. J. REISCH HUB AND SHAFT COUPLING 3 Sheets-Sheet 1Original Filed Sept. 10, 1963 INVENTOR. eorge J Rake/l HI'T RIVEK p 1968G. J. REISCH 3,399,911

HUB AND SHAFT COUPLING Original Filed Sept. 10, 1963 5 Sheets-Sheet 2 INVE'N TOR.

jp i 11 George J RedS'Ch BY m 96 4 W 30a H TORNFY Sept. 3, 1968 G. .1.REISCH HUB AND SHAFT COUPLING Original Filed Sept. 10, 1963 5Sheets-Sheet 3 INVENTOR. George J Redsrh BY fl q United States Patent3,399,911 HUB AND SHAFT COUPLING George J. Reisch, Shelton, Conn.,assignor to General Electric Company, a corporation of New York Originalapplication Sept. 10,-.1963, SenNo. 307,888, now :Patent No.3,264,016,'dated Aug. 2, 1966.'Divided and this; application Mar. 21,1966,, Ser. No. 554,222 2 Claims. (Cl. 287-753)v ABSTRACT OF THEDISCLOSURE A hub and shaft coupling for use with a molded hub comprisinga flexible latch integral with and positioned within the bore of saidhub and containing a rib-like projection which engages a groove orrecess formed on a fiattened exterior surface of the shaft. The latch isself-biased so that it positively engages the shaft at all times andthereby transmits torque to the hub assembly. The selfbiasing ofthelatch is obtained by urging its free ends radially inwardly withrespect to a portion connected to the internal wall of the hub bore.

This invention relates to an improved arrangement for coupling a hub toa shaft and more particularly to a molded hub having an integral latchfor attaching the hub to the shaft. This is a division of my copendingapplication Ser. No. 307,888, filed Sept. 10, 1963, and now U.S. PatentNo. 3,264,016.

Securing a hub to a shaft is one of the more basic manufacturingoperations, and hence any improvements in the coupling of these twocomponents are valuable contributions to the art. The improvedarrangements of this invention, although not so limited, areparticularly suitable for use in the manufacture of hubs carrying fanblades or blower wheels. In addition to being widely used as separateappliances, fans or similar rotary members are, of course, also used inmany other products such as heaters, hair dryers, and air conditions, toname just a few. In view of the large volume production of such items,any reductions in the number of parts required or improvements in theassembly procedure resulting in lower cost, can be highly significant.

It is a primary object of this invention to provide an improved low costhub and shaft coupling arrangement having a minimum number of parts andhaving simplified assembly and disassembly operations.

It is another object of this invention to provide a unique molded hubassembly including an integral self-latching means by which the hub isfirmly attached to a shaft.

It is a further object of this invention to provide an improved low costhub and shaft coupling which can be quickly assembled by hand withoutthe assistance of tools.

Yet another object of this invention is to provide a unique andsimplified hub and shaft coupling arrangement in which aforce inthedirection to withdraw the hub from the shaft will cause the hub to bemore firmly attached to the shaft.

Briefly stated, the improved coupling arrangement of this inventionrequires a shaft having a groove or recess formed in its exteriorsurface between the ends of the shaft and usually adjacent one end ofthe shaft. A molded hub, such as a type suitable for carrying fanblades, is provided having a bore for receiving the shaft and includinga flexible latch having a portion integrally formed with an internalwall of the hub bore'and a portion which is radially movable within thehub. The movable portion of the latch is formed with a radial extendinglock portion adapted to fit within the groove in the shaft. In moldingthe hub and latch, the latch is self-biased so that the lock portion isurged radially inward beyond the bore diameter.

Patented Sept. 3, 191 58 c Ice Hence, when the hub is assembled to theshaft the lock portion is forced radially outward by the shaft until thelock portion is aligned with the groove, and it then snaps radiallyinward into the groove thereby axially positioning the shaft relative tothe hub. Such an arrangement will also resist rotary movement betweenthe hub and the shaft and thus transmit torque betweenthe twocomponents. Additional molded configurations can be incorporated intothe hub bore and latch to transmit forces for higher torqueapplications.

Further features, objects and advantages will become apparent withreference to the following description and drawings wherein:

FIG. 1 is a side partially cut away view of a portable fan incorporatingthe shaft and hub coupling arrangement of this invention;

FIGS. 2-5 illustrate one embodiment of this invention with FIG. 2 beingan end view, partially sectionalized, of the fan hub and shaft assembly;

FIG. 3 is asectional view on line 33 of FIG. 2;

FIG. 4 is a sectional view on line 4--4 of FIG. 3; and

FIG. 5 is an enlarged end view of the hub bore and latch assembly;

FIGS. 6-9 illustrate another embodiment of the invention with FIG. 6being an end view of the hub assembly;

FIG. 7 is a side sectional view on line 7-7 of FIG. 6;

FIG. 8 is a sectional view on line 8-8 of FIG. 7; and

FIG. 9 is a side elevational view, partially sectionalized, of theassembled hub and shaft;

FIGS. l0l3 illustrate another embodiment of this invention very similarto the embodiment of FIGS. 6-9;

FIG. 10 is an end view of the hub assembly;

FIG. 11 is a sectional view of the hub assembly on line 1111 of FIG. 10;

FIG. 12 is a sectional view of the hub assembly on line 12-12 of FIG.11; and

FIG. 13 is a side elevational view, partially sectionalised, of theshaft and -hub assembly;

FIGS. 14-16 illustrates a final embodiment of the invention with FIG. 14showing an end view, partially sectionalized, of the hub assembly;

FIG. 15 is a side sectional view on line 1515 of FIG. 14; and

FIG. 16 is a side elevational view, partially sectionalized, of the huband shaft assembly;

As previously mentioned, the unique hub and shaft assembly of thisinvention, while being suited for a wide variety of applications, isparticularly useful in mass produced items such as electric fans orsimilar products. Hence, by way of example, there is shown in FIG. 1

an electric fan including a motor within housing 2, an

output shaft 4, a fan blade hub 6 carrying a plurality of blade elements8, a fan guard 10, and a suitable supporting structure 12. Since theinvention relates to the shaft and hub coupling arrangement, furtherdetails of the remainder of the fan will not be given. The hub 6 andshaft 4 shown in FIG. 1 are representative of the exterior views of thevarious embodiments of the invention which will be hereinafterdescribed.

In the embodiment of FIGS. 25 there is shown a shaft 14 having acircular cross-section with an elongated recess or chordal segmentremoved from one end of the shaft leaving an elongated, rectangular,flat exterior surface 16 on one side of the shaft end. A groove 18having a semicircular cross-section or other desirable configuration isformed in the flat surf-ace 16 closely adjacent the shaft end;preferably, the groove extends transversely or in substantiallyperpendicular relation to the shaft axis.

The other component of the coupling is the hub 20 shown having molded inor mechanically fastened blades 8 and having an internal bore 22 adaptedto snugly receive the shaft 14. In accordance with the invention, the

3 hub 20 is provided with a integrally formed with an internal wall ofthe hub bore 22. As seen in the drawings, the latch 24 is an elongatedmember extending from one endof the hub bore to slightly beyond theother end of the bore. The latch has a rectangular shape-with an axiallyextending radially inner. fiat surface 24a and an axially extendingradially outer flat surface 241). The end 240 of the latch 24 remotefrom theshaft end, is integrally joined with a side wall of the housingbore 22 by a connecting section 26. As can be seen from FIGS. 2 and 4,the connecting section 26 is merely an extension of one edge of thelatch adjacent end 24c and the section extends throughout apredetermined axial length which in the arrangement shown is nearly halfthe length of the latch. Section 26 is positioned so that the end of theshaft fits within the space bounded by latch surface 24a and theadjacent walls of the bore 22. In this manner latch surface 24a engagesthe flat surface 16 on the end of shaft 14. Or stated differently, latch24 fits within the elongated recess or chordal is urged inwardly. Hence,when the shaft is inserted within 1 the hub, the self-biasing nature ofthe latch urges the portion of inner flat surface 24a adjacent edge 24etightly into engagement with shaft flat surface 16. This cooperationbetween the shaft 14 and latch 24 together with connecting section 26serves to transmit torque between the I shaft and the hub and preventsrelative rotation between the two components. It should be noted thatwith the hub as shown in FIG. 5, the shaft 14 is preferably rotated in aclockwise direction so that the shaft drives against the connectingsection 26.

To prevent the hub from being axially withdrawn from the shaft, themovable end 24d of latch 24 is formed with a radially inwardly extendingrib-like projection 28 having a semicircular cross-section or otherdesirable configuration and adapted to fit within the shaft groove 18.In assembling the hub to the shaft, the rounded surface of the rib-likeprojection 18 engages the end of the shaft so that the movable end 24dof the latch is moved radially outwardly to permit the hub to be fullyplaced onto the shaft. It should be noted that the latch is positionedsuch that the bore is spaced radially outward from the outer surface 24bof the latch so that the latch end 24d can be moved outwardly asufficient distance to accommodate the rib-like projection 28. When theprojection is aligned with the groove 18 it snaps inwardly into thegroove due to the self-biasing of the latch. Thus, with thisinterlocking of the rib and groove, the hub is effectively positioned onthe latch without the use of set screws or any such similar additionalparts or components. It should be noted that since the latch extendsthroughout the axial length of the hub and most of the latch surface 24awill always be in contact with flat surface 16 while the entire edge24ewill be under pressure with surface 16, the hub will not rock or tiltwhen an axial force is applied to the hub or blades attached thereto.

While the hub assembly is not limited to being made of a specificmaterial, it is the use of plastics or similar moldable materials whichmakes this invention practical and worthwhile. With such materials theentire hub assembly, including the latch 24 and the lock portion 28, ismolded into a single "component. With the continual improvements beingmade in plastics, there are many low cost types available which have thenecessary strength and heat withstanding characteristics. The one-pieceplastic hub construction is particularly advantageous from the latchmember or element- 24.

.standpoint that the hub can be assembled to the shaft in a one stepoperation without the use of any tools. The disassembly operation issimilarly very easy in that it is only necessary to lift the movable end24d of the latch so that the lock portion 28 is free of groove 18, andthen the hub can be easily withdrawn. Usually a screw driver or similartool can be used to pry the latch end 24 outwardly. v

Referring now. to the embodiment of FIGS. 6-9, the coupling arrangementshown therein retains the basic concept of a molded hub assembly havingan integral latch member but introduces several variations from that ofthe previous embodiment. As seen in 'FIG. 9, the shaft 14 issubstantially the same as the shaft shown in FIG. 3 in that it has aflattened surface 16 on one end of the shaft and has a transverselyextending semicircular groove 18 in the flat surface 16 adjacent the endof the shaft.

In accordance with this embodiment of the invention, however, the latchmember 30 is connected at a location near its mid-section to the sidewall of bore 32 of hub 33. More specifically, the latch 30 is connectedby a radially extending connecting strut or section 34 which also servesas a fulcrum for the latch. With such an arrangement, moving one end 30dof the latch in one direction, say radially outwardly, will move theother end 300 of the latch radially inwardly.

The hub 33 is molded so that end 30d of the latch normally extendsradially inwardly with respect to the connecting fulcrum 34 and withrespect to the opposite latch end 360, as clearly shown in FIG. 7. Arib-like lock portion 36 extends radially inwardly from end 30d of thelatch. The lock portion is given a semicircular cross section whichmates with the cross section of groove 18 formed in the end of shaft 14.

As can be seen from the drawings, latch 30 has an inner fiat surface 30aand an outer fiat surface 30b. The inner flat surface 30a and theopposing portions of the bore 32 define a space adapted to receive theflattened end of shaft 14. The distance between the inner flat surface30a in the area adjacent the latch end 300 to the opposing wall of bore32 is such that the shaft end can be inserted into the hub bore withoutappreciable interference. However, as the shaft is inserted further, theend of the shaft engages the inwardly extending latch end 30d causing itto be forced radially outwardly within the space between the latch endand the outwardly adjacent wall of bore 32. As the shaft end engageslock portion 36, latch end 30d will naturally be forced further radiallyoutwardly. When the lock portion 36 is aligned with shaft groove 18,latch end 30d will snap inwardly into locking position. Thus, theself-biasing of the latch will hold the lock portion in position toprevent axial movement of the shaft relative to the hub. Since the latchend 30d is forced radially outwardly by the shaft end, the oppositelatch end 300 is forced radially inwardly due to the pivotal action ofthe latch about the fulcrum 34. This causes both ends of the latch fiatsurface 30a to be urged into firm contact with the shaft flat surface 16so that the hub is held tightly in position. It is important to notethat since the latch 30 extends throughout the axial length of the hub,a tight connection is maintained thereby preventing tilting or wobblingof the hub on the shaft.

The engagement of latch surface 30a with shaft surface 16 transmits acertain amount of torque between the shaft and the hub and also preventsrotary looseness between the components. However, for high torqueapplications, it is desirable that additional torque transmitting meansbe provided. For this purpose, the hub bore 32 has been formed with twoinwardly extending shoulders 38 and 40, as seen in FIG. 6. Theseshoulders are positioned to engage the edges of shaft flat surface 16 tosatisfactorily transmit torque between the two components in eitherdirection. It should be realized, however, in view of desirablemanufacturing tolerances, the shaft end may not be tightly positioned,by the shoulders 38 and 40aud that this function is provided by thelatch 30 as heretofore de- From FlG.6 -it can also beseen thatonlytheportion of the bore which will engage the shaft exteriorsurface needconform to such surface. The remainingportion of the bore may be giventhe configuration desired to obtain proper strength. characteristics andease of molding.

The embodiment of the invention described in FIGS. -13 is basicallysimilar to that ofv the embodiment in FIGS. 6-9 with the majordifferencebeing that there is provided a fulcrum strut or connecting section 42extending between the latch30 and hub bore 32 which is not radiallyaligned as is the fulcrum 34 in FIGS. 6-9. Instead, the fulcrum strut 42as best seen in FIGS. 11 and 13 slopes at an angle from the hub boretoward the latch end 30d, or in other words, toward the lock portion 36or the end of the latch normally positioned adjacent the end of theshaft to be received within the bore. More specifically, the fulcrumstrut 42 forms acute angles 44 and 45 with the wall of bore 32 extendingtoward the shaft end and with the outer flat surface 30b of latch end300. It has been found that an angle of about 45 is preferable. Strut 42naturally forms complementary obtuse angles 46 and 47 with the wall ofbore 32 extending away from the shaft end and with surface 30b of latchend 30d. The strut relationship might also be expressed by stating thatthe end of the hub adjacent the shaft end is closer to the end of thestrut attached to the latch than it is to the end of the strut attachedto the hub bore.

The purpose for the angled strut arrangement is to minimize thepossibility of inadvertent removal of the hub from the shaft by an axialwithdrawal force on the hub. Referring to FIG. 13, it will beappreciated that if a force is applied to the hub in an axial directionto withdraw the hub from the shaft, lock portion 36 in groove 18prevents removal and strut 42 in effect tries to become radiallyaligned. This action uniquely causes the latch 30 and its lock portion36 to become more tightly engaged with the shaft whereby inadvertentremoval is made more diflicult. The latch of FIGS. 10-13 naturally alsoprovide the other advantages previously described in connection with thelatch of FIGS. 6-9.

One additional slight dilference between the embodiment of FIGS. 10-13and that of FIGS. 6-9, as perhaps best seen in FIG. 10, is that thedistance from the latch upper fiat surface 30b to the outwardly adjacentwall of bore 32 is slightly greater than the corresponding distanceshown in FIG. 6. This additional space is merely provided to accommodatethe angled fulcrum strut 42. Naturally these dimensions may be varied tosuit the particular application.

Referring now to a final embodiment of this invention illustrated inFIGS. 14-16, there is shown a molded hub 50 having a bore 52 adapted toreceive a shaft 54. The end of the hub to be positioned adjacent the endof the shaft is provided with a pair of diametrically opposed latchmembers 56 and 58 each having one end 560 and 580 formed integrally withthe walls of bore 52. The opposite ends 56d and 58d of the latches arefree to flex radially; and in accordance with the invention, the latchesare molded so that in an unrestrained position, as shown in FIG. 15, thefree ends 56d and 58d of the latches extend radially inwardly into theinterior of the bore.

To accommodate radially outward movement of the latches 56 and 58, thehub 50 has been formed with a pair of enlarged arcuate recesses 60 and62. As can be seen recess 62 is positioned radially outwardly from latch56 and recess 62 is positioned radially outwardly from latch 58. Theradially outer surfaces of the latches are arcuate, as best seen in FIG.14 to cooperate with the recesses 60 and 62.

As shown in FIG. 16, shaft 54 is provided with a pair of grooves 68 and70 formed on opposite sides of the end of the shaft. Having rectangularcross sections with flat inner surfaces68a and 70a, t he grooves extendin a direction substantially perpendicular to the shaftaxis- The latches56 and 58 are formed with inwardly extending lock por tions 64 and 66 tomate with the grooves 68 and 70. It-will be understood that when theshaft 54 is inserted Within the hub- 50, the end ofthe shaft engages thesloping cam surfaces 64b and 66b of the lock portions causing thelatches to be smoothly moved radially outwardly into the enlargedrecesses 60 and 62. When the lock portions are aligned with the grooves68 and 70, the latches snap radially inwardly causing the lock portions64 and 66 to snap intothe respective grooves. As can be seen, the flatsurfaces 64a and 66a of the lock portions cooperate with the fiatsurfaces 68a and 70a of the grooves respectively. Also, surface 660 oflock portion 66 engages surface 700 of groove 70. In this manner thelock portions 64 and 66 are firmly engaged with the grooves in the shaftto prevent removal of the hub from the shaft by axially directed forces.

The arrangement of FIGS. 14-16 is primarily suitable for low torqueapplications in that while the latches 56 and 58 transmit torque, thehub can be removed from the shaft by holding the shaft and forciblyrotating the hub. When such force is applied, the lock portions 64 and66 will slide arcuately out of the grooves 68 and 70. Such removaloperation is very simple if a portion of the shaft is exposed forgripping purposes. In the event the shaft is not accessible the hub maybe removed in the same fashion as the previous embodiment of theinvention; namely, by prying the ends of the latches radially outwardlyaway from the shaft to lift the lock portions out of the shaft groovesand then subsequently applying an axial force to withdraw the hub fromthe shaft.

If it is desirable to use the embodiment of FIGS. 14-16 for highertorque applications, additional torque transmitting means can be easilyincorporated into the arrangement. For example, the grooves 68 and 70may be formed more into the shape of sockets rather than grooves havinga flat surface forming a chord of the shaft. With such an arrangement itis very difficult to rotate the hub relative to the shaft, so that thelock portions can not be removed from their mating recesses in thisfashion.

It should be noted that the latch members 56 and 58 do not extendthroughout the axial length of the bore 52 but that instead they extendonly about half the axial distance. Nevertheless, it should be realizedthat they may extend considerably further toward the opposite end of thehub if desired, so long as there is sufficient material to connect thelatch to the hub.

The coupling arrangement of this invention including the unique moldedhub and self-biased latches are very advantageous in that additionalparts such as setscrews or keys and the necessary assembly tools are notrequired. Also, the hole tapping operation needed with setscrews andadding of adhesive or other means for locking are eliminated. Anothermethod of attaching a plastic hub to a shaft is by knurling the shaftsurface and forcing the hub onto the shaft. While this method does notrequire additional parts, the assembly procedure is more difficult thanwith the one step operation required of the present invention. Moreover,with the present invention, the assembly operation does not affect thebalance of the hub and shaft whereas the forcing method may. Thedisassembly step of the couplings of the invention is also very simpleand easy.

While there has been described several different embodiments of theinvention, other variations and modifications may now become apparent toone skilled in the art. Accordingly, it is intended that the attachedclaims should include all such variations and modifications which fallwithin the true spirit and scope of the invention.

What is claimed is:

1. A hub and shaft coupling comprising a shaft of circular cross sectionhaving a recess on one end of the shaft leaving a fiat exterior surfaceformed on one side of the shaft end, a molded hub having a bore forreceiving said flat shaft end, a flat elongated flexible latch axiallyextending within said hub bore, a part of one elongated edge adjacentone end of said latch integrally connected with an internal wall of saidhub bore and having its opposite end and opposite elongated edge spacedfrom thebore free to flex within the bore, said latch being adapted tofit within the area defined by said shaft recess such that the flatsurface of the latch engages said shaft flat surface and such that oneedgeof the shaft flat surface engages said integral latch connection totransmit torque between the shaft and the hub, said latch beingself-biased to a position wherein said flat surfaces are tightly urgedinto engagement along the axial length of the bore and also transverseto the axis of the bore, a groove formed in said shaft flat surface, anda radially extending lock portion formed integrally on a movable portionof said latch and adapted to fit within said shaft groove to resistaxial movement between the hub and shaft.

2. A hub and shaft coupling comprising a shaft of circular cross sectionhaving a recess on one end of the shaft leaving a flat exterior surfaceformed on one side of the shaft end, a molded hub having a bore forreceiving said shaft end, an elongated flexible latch having part of theside adjacent one end integrally formed with an internal wall of saidhub bore along a part of the axial length of said bore and having itsopposite end and opposite side spaced from the bore free to flex withinthe bore, said latch being adapted to fit within the area defined bysaid shaft recess, said latch being positioned within said hub such thata flat surface of the latch is adapted to engage said shaft flat surfaceand such that one edge 'of the shaft flat surface engages the portion ofsaidhub connecting the latch to the wall of said bore to transmit torquebetween the shaft and hub, said latch being self-biased to a positionwhereinsaid flat surfaces are urged into engagement both along the axiallength of the bore and also transverse to the bore axis, a groove formedin said shaft flat surface and extending transversely to the shaft axis,and a radially extending rib-like lock portion formed integrally on thefree end of said latch and adapted to fit within said shaft groove toresist movement between said hub and said shaft.

References Cited UNITED STATES PATENTS 2,189,845 2/ 1940 Terrill 287-532,269,208 1/1942 Kimball 28753 2,668,973 2/1954 Glaza et al 15-1762,733,083 1/1956 Strange 28753 3,084,852 4/1963 Seavey 230-246 3,187,5216/1965 Morris et al 2871 19 3,193,312 7/1965 Ehner 292-349 3,256,031 6/1966 Fillweber 287-1 19 EDWARD C. ALLEN, Primary Examiner.

A. V. KUNDRAT, Assistant Examiner.

